To me, defense by a catcher far outweighs what they can do on offense.
I've always been one to believe a catcher's defense goes far beyond just catching the ball, throwing out base runners, blocking bad pitches and framing balls into strike calls. How they handle the pitching staff is underrated, IMO. Whether it's building a comfort zone, providing a steady target to throw to or calling the right pitch, at the right time (although some teams call almost all pitches from the bench, these days) or settling down a shaken pitcher, a catcher's job extends beyond data and stats, more than any other position.
It's not something you can easily prove, but ask almost every MLB pitcher who ever existed, if the catcher makes a significant difference, and I'll bet over 90 to 95% say yes. That has to count for something.
The CERA stat has been misunderstood and misused for years, as is OPS Against by catcher. It's a highly limited stat that only has use when comparing catchers catching the same pitchers over the same season, and even then, it's not perfect and often involves unbalanced sample sizes and small to tiny sample sizes. It's more about the theory that some catchers get more out of the same pitchers than others do or would be expected to do, had they been that team's catcher, instead. I'll go to my grave thinking some catchers make a huge difference beyond blocking, framing and CS rates.